Akin sheds 8 points overnight to near-tie

August 21st, 2012, 1:23am by Sam Wang

A new poll from PPP(D) gives Akin 44%, McCaskill 43%. The pollster says there’s “little difference” from before, as does Josh Marshall. Normally I don’t like to comment on one poll. But this interpretation is likely to be erroneous for two reasons.

First, PPP is making a comparison with its own previous poll in mid-May, showing the same numerical margin (Akin 45, McCaskill 44). It is more appropriate to make a comparison with polls conducted after the August 6th primary, since after a primary a nominee’s support firms up considerably.

Akin was +3% (median, n=3) before August 6th, and +11% (n=1) afterward — an 8-point bounce. So if he is unchanged since May, then he must have lost all this gain. An 8-point loss in one day is an enormous drop. Another comparison that makes the same point is that going from +11% to +1% (PPP) is a 10-point drop. Again, this is very large.

Why did PPP fail to notice this? Because they didn’t have an August 7th poll, and no way would they cite another pollster. This leaves them with a May-vs.-August comparison – and a major analysis error.

Second, even if we accept the premise of comparing with May, PPP has made a statistical error in claiming that a 1-point change indicates a lack of change. When comparing a candidate’s support between two polls, the difference has a standard deviation of about 3.5% and the 95% confidence interval is about +/-7%. All PPP can say from their own data is that since May, Akin’s support changed between -8% and +7% (95% CI). This is not very informative. But it does show how useful poll aggregation can be.

In the short term, this should make both Akin and McCaskill supporters more likely to contribute to their candidates, since the race is now probably on the edge. What happens in the long term is less clear. Is Akin too damaged to continue? Or will he soldier on?

18 Comments so far ↓

It will be interesting to see if this all really changes this race much. Call me cynical, but given the rightward surge of the Republican party I find it hard to believe that his statements will change the outcome of this race. From what I have been able to gather from my readings, his opponent is hated almost as much as President Obama in Missouri.

One more thing: I keep waiting for the “Ryan Bounce” to subside — but that does not yet seem to be happening. Quite the contrary, Obama’s EV estimate keeps being reduced as, it seems, the GOP have managed to put additional states into play.

Moreover, the Republican National Convention starts in less than a week, which I understand can be expected to provide an additional bounce.

To put it bluntly: I am worried…
I am worried that this surge in the polls and EV estimates may fire up the Republican base, while disheartening the Democratic base — which in turn could have a decisive influence on relative turnouts on election day.

For reasons of statistical sampling alone, there’s a considerable bit of uncertainty in interpreting any one poll. Time will tell, assuming Akin stays in past today, the deadline for withdrawing easily.

Olav: I’m not convinced that most of what you’re seeing is real motion in the race.

First of all, contrary to what I said in another recent comment, several pollsters are now applying their likely-voter screens, which tends to remove a slight pro-Democratic slant that was there before.

Second, the motion in the EV count is within the range of variation of what we’ve seen since the beginning of summer, and judging from this site and from other aggregators of polls, I’m not convinced that anything has really significantly changed in the race since Romney clinched the nomination. Before the Ryan pick, Obama was at a maximum or near-maximum for the past few months, but it probably wasn’t anything more than the effect of some outlier polls.

I’d also caution anyone prone to get worried to just stop watching polls until the conventions are over, because the conventions are going to make them swing around a lot over the very short term.

I second Olav’s request. That is a huge switch in Florida in a short time. Are you including in your polls the recent one in Florida showing a Romney lead of 15 points? Nate Silver did an analysis of this poll and suggested that it is seriously flawed in its assumptions. Any comments?

The PPP poll was a “flash” poll, conducted over 3 hour time slice. Interestingly, the positive results from that poll (post the “secreting a secretion” prevents pregnancy in the case of “legitimate” rape gaffe) will encourage Akin to stay in the race.
Ben Smith says Akin bought ads for the 22-27, and Akin is not making any motions to step aside, inspite of the brays and howls from Limbaugh and Hannity.
Im dubious of the Ryan bump.
Sure the landlines love Ryan.
But there are at least two distinct cell phone demographics– cell-only households, and smartphone users. I think both are resistant to traditional polling techniques.
But just because those demos are unlikely to be polled, doesnt mean they are unlikely to vote.